Viewers of last night’s mayoral debate may have puzzled over why, at an event designed for the four Democratic candidates to tear one another down, opponents of Rep. Anthony Weiner went out of their way to pick him up – and why they mysteriously offered the congressman get-well wishes.

The usually irrepressible Mr. Weiner did not identify his ailment at last night’s debate. Followers of his campaign, however, had spent much of the day wondering whether excruciating pain from an early morning kidney stone would keep the congressman, who has consistently placed near the bottom of the Democratic pack in public-opinion polls and who suffers from low name recognition, from participating in the debate at all.

According to a spokesman for Mr. Weiner, Anson Kaye, the congressman awoke in the pre-dawn hours yesterday to “significant pain,” and at 5 a.m. went to the emergency room at Parkway Hospital in Forest Hills, Queens, where he spent six hours before being diagnosed with a kidney stone.

The campaign canceled a speech and other public appearances planned for yesterday afternoon and warned that Mr. Weiner, who spent the rest of the day recovering at home, might skip the debate. Meanwhile, questions surfaced as to whether the stone might also keep him from receiving around $1 million from the New York City Campaign Finance Board, which requires participation in official debates for candidates to receive public matching funds. Less than two hours before the debate, however, the campaign announced that Mr. Weiner would forfeit neither matching funds nor a chance to increase his visibility among the electorate, and would participate.

If Mr. Weiner’s appearance at last night’s televised forum seemed brave to viewers, it was in keeping with his general response to his ailment, the urologist who treated Mr. Weiner at Parkway, Edward Moss, said yesterday.

“Pain from a kidney stone is considered the most severe pain the body can experience,” Dr. Moss said. Although Dr. Moss – whose brother Mitchell is an unpaid adviser to Mayor Bloomberg – said he was unable to comment on the specifics of Mr. Weiner’s treatment, he said the congressman had been “stoic” throughout his emergency-room ordeal, adding that it was possible Mr. Weiner would experience intermittent pain throughout the day and into the debate.

Perhaps indicating that Mr. Weiner was suffering more than he let on last night, the congressman, when asked by the moderator of last night’s debate, NY1’s Dominic Carter, to explain his situation, responded by thanking the staff of “Parkside” for his treatment. Mr. Weiner was treated at Parkway Hospital. Parkside is a funeral home in Forest Hills.